The invention relates to a silver halide color photo-sensitive material which is highly color developable, and forms a magenta dye image improved in preservability, and especially improved in light resistance. Further detailedly, the invention relates to a silver halide color photo-sensitive material which contains a novel magenta-forming coupler of 1H-pyrazolo[3,2-C]-s-triazole type.
In general, a silver halide color photo-sensitive material exhibits a dye image by that exposed silver halide grains are reduced by a color developing agent of aromatic primary amine type, and that therewithal produced oxidation product of said color developing agent is coupled with yellow-, magenta-, and cyan-forming couplers.
While the coupler conventionally used to form said magenta dye has been of pyrazolone type, it has shortcomings of exhibiting undesirable secondary absorptions, and of being poor in preservability, and especially in formaldehyde gas resistance.
For the purpose to overcome such shortcommings as the above, various magenta-forming couplers of 1H-pyrazolo[3,2-c]-s-triazole type have been proposed so far. These couplers, which have been described in U.S. Pat. No. 3,725,067, and British Patent Nos. 1,252,418 and 1,334,515, for example, surpass magenta-forming couplers of pyrazolone type in terms of elimination of secondary absorptions, but are still insufficient in improvement of formaldehyde resistance and are little improved in light resistance of dye image. Compounds described in Research Disclosure, No. 12443 also can not be put to practical use of the art in terms of color developability at all. Magenta-forming couplers of 1H-pyrazolo [3,2-c]-s-triazole type, described in Japanese Patent O.P.I. Publication No. 2045/1983, is considerably improved in formaldehyde resistance of dye image, and in color developability, but is still little in terms of light resistance of dye image.
Couplers described in Japanese Patent O.P.I. Publication Nos. 99437/1984 and 125732/1984 also are improved in color developability, but less improved in light resistance of dye image. In case of those described in the latter Publication No. 125732/1984, the light resistance of dye image is not improved without combined use of another certain additive. Only the coupler of Compound No. 19 in the specification of the former Publication No. 99437/1984 is somewhat improved in light resistance of dye image, but still unsatisfactory.
Thus, while magenta-forming couplers of 1H-pyrazolo [3,2-c]-s-triazole type have been paid attention to because of their elimination of secondary absorptions, and high formaldehyde resistance, it should be noted that they have been little improved in terms of light resistance of dye image so far.
The object of the invention is to present a silver halide color photo-sensitive material which is not only excellent in both light resistance, and formaldehyde resistance, but also high in color developability.
The above object of the invention is attained by a silver halide color photo-sensitive material having at least one silver halide emulsion layer on a support, characterized by that said silver halide emulsion layer contains at least one magenta-forming coupler of 1H-pyrazolo[3,2-c]-s-triazole type which is substituted by a tertiary alkyl group at the 3-position, and by another releasable group than a hydrogen atom at the 7-position.
As a result of keen studies aiming at solution of aforementioned problems, the inventors came to find magenta-forming couplers of 1H-pyrazolo[3,2-c]-s-triazole type which were excellent in both formaldehyd resistance, and light resistance of image, and high in color developability.
They are couplers of 1H-pyrazolo[3,2-c]-s-triazole type each of which is substituted by a tertiary alkyl group at the 3-position, and by another releasable group than a hydrogen atom at the 7-position, In other words, it was found that 1H-pyrazolo[3,2-c]-s-triazole compounds were made to largely improve in light resistance of image, and were given a high color developability by having been substituted by a tertiary alkyl group at the 3-position, and by another releasable group than a hydrogen atom at the 7-position.
As for said releasable group, the 7-position of a 1H-pyrazolo[3,2-c]-s-triazole compound is the position where said compound couples with the oxidation product of a color developing agent to form a magenta dye, and said releasable group at the 7-position is released through said coupling reaction
Said 1H-pyrazolo[3,2-c]-s-triazole compound which is substituted by a tertiary alkyl group at the 3-position, and by another releasable group than a hydrogen group at the 7-position, is represented the following general formula: ##STR1## where R.sub.1 is a tertiary alkyl group; R.sub.2 is an alkyl, aryl or heterocyclic group. X is another releasable group than a hydrogen atom, which is released through coupling reaction of said compound with the oxidation product of a color developing agent.
The tertiary carbon atom of said tertiary alkyl group represented by R.sub.1 is allowed to be substituted by, instead of an alkyl group, such an aryl group as a phenyl group; an alkoxy group an aryloxy group, an alkylthio group or the like. In addition, said tertiary carbon atom is allowed to participate also in the formation of another cyclic group. Furthermore, an alkyl group attached to said tertiary carbon atom is allowed to be substituted by a halogen atom; such an aryl group as a pheny group; a cyano group; a substituent group which links through a carbonyl group, such as an alkoxycarbonyl, acyl, or carbamoyl group; or a substituent group which links through a hetero atom, such as a nitro,alkoxy, alkylthio, arylthio, alkylsulfonyl, arylsulfonyl, alkylsulfinyl, arylsulfinyl, or dialkylamio group. Such a substituent group is especially preferably selected from among alkylthio, alkylsulfonyl, arylsulfonyl, alkylsulfinyl, and arylsulfinyl groups.
Further, needless to say, magenta-forming couplers in the invention include also bis-type 1H-pyrazolo[3,2-c]-s-triazole compounds, which are formed when the heterocyclic residue is a 1H-pyrazolo[3,2-c]-s-triazol-3-yl residue.
Such tertiary alkyl groups as above substantially include tert-butyl, 1,1-dimethyl-2-methoxyethyl, 1,1-dimethyl-2-cloroethyl, 1-methyl-1-phenylethyl, 1,1-di-n-amylhexyl, 7,7-dimethylnorbornan-1-yl, 1,1-dimethylbutyl, 1-ethyl-1-methylpropyl, and adamantyl groups.
The alkyl group represented by R.sub.2 is allowed to be either primary, or secondary or tertiary, and to be substituted by a cyclic group, or any of the same substituent group as those for R.sub.1 cited above.
The aryl group represented by R.sub.2 is preferably a substituted or unsubstituted phenyl group. Substituent groups for said substituted group include alkyl, halogen, hydroxy, cyano, nitro, alkoxy, acylamino, sulfonamido, alkoxycarbonyl, carbamoyl, and carboxy group.
The heterocyclic group represented by R.sub.2 is substantially a furyl, thienyl, or pyridyl group, or the like. Such a heterocyclic group is allowed to be substituted by any of the same substituent groups as those for the above aryl group as R.sub.2.
The releasable group represented by X is allowed to be a halogen atom, or an organic group linked through an oxygen, nitrogen, or sulfur atom.
Among such releasable groups, those liked through an oxygen atom include alkoxy, aryloxy, acyloxy, and heterocyloxy groups. Those linked through an nitrogen atom include acylamino, diacylamino, and sulfonamido groups, and said-nitrogen-containing 5- or 6- membered heterocyclic groups. Those linked through an sulfur atom include thiocyano, alkylthio, arylthio, heterocyclothio, arylsulfonyl, and alkylsulfonyl groups.
Exemplary compounds embodied based on the invention are listed below, but the invention is not limited thereto: ##STR2##
Description of typial synthetic processes of the above couplers of the invention is given below. The experimental synthesis was carried out on referring to the description in Research Disclosure, No. 12443; Journal of the Chemical Society I, 1977, P. 2047-2052; U.S. Pat. No. 3,725,067; and Japanese Patent C.P.I. Publication No. 99437/1984.